[bezier curve] add missing files

src/modules/math/BezierCurve.cpp

@@ -0,0 +1,146 @@
+/**
+ * Copyright (c) 2006-2013 LOVE Development Team
+ *
+ * This software is provided 'as-is', without any express or implied
+ * warranty.  In no event will the authors be held liable for any damages
+ * arising from the use of this software.
+ *
+ * Permission is granted to anyone to use this software for any purpose,
+ * including commercial applications, and to alter it and redistribute it
+ * freely, subject to the following restrictions:
+ *
+ * 1. The origin of this software must not be misrepresented; you must not
+ *    claim that you wrote the original software. If you use this software
+ *    in a product, an acknowledgment in the product documentation would be
+ *    appreciated but is not required.
+ * 2. Altered source versions must be plainly marked as such, and must not be
+ *    misrepresented as being the original software.
+ * 3. This notice may not be removed or altered from any source distribution.
+ **/
+
+// LOVE
+#include "BezierCurve.h"
+#include "common/Exception.h"
+
+#include <iostream>
+
+using namespace std;
+
+namespace
+{
+
+/**
+ * Subdivide Bezier polygon.
+ **/
+void subdivide(vector<love::Vector> &points, int k)
+{
+	if (k <= 0)
+		return;
+
+	// subdivision using de casteljau - subdivided control polygons are
+	// on the 'edges' of the computation scheme, e.g:
+	//
+	// ------LEFT------->
+	// b00  b10  b20  b30
+	// b01  b11  b21 .---
+	// b02  b12 .---'
+	// b03 .---'RIGHT
+	// <--'
+	//
+	// the subdivided control polygon is:
+	// b00, b10, b20, b30, b21, b12, b03
+	vector<love::Vector> left, right;
+	left.reserve(points.size());
+	right.reserve(points.size());
+
+	for (size_t step = 1; step < points.size(); ++step)
+	{
+		left.push_back(points[0]);
+		right.push_back(points[points.size() - step]);
+		for (size_t i = 0; i < points.size() - step; ++i)
+			points[i] = (points[i] + points[i+1]) * .5;
+	}
+	left.push_back(points[0]);
+	right.push_back(points[0]);
+
+	// recurse
+	subdivide(left, k-1);
+	subdivide(right, k-1);
+
+	// merge (right is in reversed order)
+	points.resize(left.size() + right.size() - 1);
+	for (size_t i = 0; i < left.size(); ++i)
+		points[i] = left[i];
+	for (size_t i = 1; i < right.size(); ++i)
+		points[i-1 + left.size()] = right[right.size() - i - 1];
+}
+
+}
+
+namespace love
+{
+namespace math
+{
+
+BezierCurve::BezierCurve(const vector<Vector> &pts)
+	: controlPoints(pts)
+{
+}
+
+const Vector &BezierCurve::getControlPoint(int i) const
+{
+	if (i < 0)
+		i += controlPoints.size();
+
+	if (i < 0 || i >= controlPoints.size())
+		throw Exception("Invalid control point index");
+
+	return controlPoints[i];
+}
+
+void BezierCurve::setControlPoint(int i, const Vector &point)
+{
+	if (i < 0)
+		i += controlPoints.size();
+
+	if (i < 0 || i >= controlPoints.size())
+		throw Exception("Invalid control point index");
+
+	controlPoints[i] = point;
+}
+
+void BezierCurve::insertControlPoint(const Vector &point, int pos)
+{
+	if (pos < 0)
+		pos += controlPoints.size() + 1;
+
+	if (pos < 0 || pos > controlPoints.size())
+		throw Exception("Invalid control point index");
+
+	controlPoints.insert(controlPoints.begin() + pos, point);
+}
+
+Vector BezierCurve::eval(double t) const
+{
+	if (t < 0 || t > 1)
+		throw Exception("Invalid evaluation parameter: must be between 0 and 1");
+
+	// de casteljau
+	vector<Vector> points(controlPoints);
+	for (size_t step = 1; step < controlPoints.size(); ++step)
+		for (size_t i = 0; i < controlPoints.size() - step; ++i)
+			points[i] = points[i] * (1-t) + points[i+1] * t;
+	
+	return points[0];
+}
+
+vector<Vector> BezierCurve::render(size_t accuracy) const
+{
+	vector<Vector> vertices(controlPoints);
+	subdivide(vertices, accuracy);
+	return vertices;
+}
+
+
+} // namespace math
+} // namespace love